Numerical and Experimental Study of the Propulsive Speed of the Three Joint Bending Propulsion Mechanism

1996 ◽  
Vol 118 (1) ◽  
pp. 134-141 ◽  
Author(s):  
Motomu Nakashima ◽  
Kyosuke Ono
Keyword(s):  
Experimental Study ◽  
Numerical Method ◽  
Coupled System ◽  
Vortex Method ◽  
Simplified Model ◽  
Two Dimensional ◽  
Discrete Vortex ◽  
Discrete Vortex Method ◽  
Propulsion Mechanism ◽  
Phase Differences

The three joint bending propulsion mechanism as a simplified model offish propulsion is investigated. A numerical method for a coupled system of the bending propulsion mechanism and the fluid is developed, based on the two-dimensional discrete vortex method. The characteristics of the propulsive speed of the three joint bending propulsion mechanism are numerically and experimentally investigated. It is found that the propulsive speed has a maximum numerical and experimental value when all the phase differences of the joints are about zero for four amplitude patterns. The experimental propulsive speeds are found to be 65 ∼ 80 percent of the numerical ones.

Numerical Study of the Thrust, Energy Consumption, and Propulsive Efficiency of a Three Joint Bending Propulsion Mechanism

2000 ◽  
Vol 122 (3) ◽  
pp. 614-618 ◽  
Author(s):  
Motomu Nakashima ◽  
Kyosuke Ono
Keyword(s):  
Energy Consumption ◽  
Numerical Method ◽  
Numerical Study ◽  
Vortex Method ◽  
Propulsive Efficiency ◽  
Discrete Vortex ◽  
Discrete Vortex Method ◽  
Propulsion Mechanism ◽  
Maximum Value ◽  
Phase Differences

In our previous paper, we proposed a numerical method based on the discrete vortex method for a bending propulsion mechanism of fish or cetaceans in water, and we demonstrated its validity by comparing the results with an experiment using a three joint bending propulsion mechanism. In this paper, using this numerical method, we will analyze the characteristics of the thrust, energy consumption, and propulsive efficiency of a three joint bending propulsion mechanism in terms of normalized propulsive speed and the phase differences of the adjacent joints. We found that the thrust decreases due to the increase in the lift force as the normalized propulsive speed increases when all the joints move in phase. We also found that the propulsive efficiency has a maximum value when the normalized propulsive speed is 0.8 and when all the phase differences between the joints are 100 degrees. [S0098-2202(00)01203-7]

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